snapcraft automatically adds <stage>/usr/bin and <stage>/usr/sbin, additionally those paths are added to the beginning. This would usually work for native builds, but causes problems when running cross builds e.g. including python in the snap, would make the next part fail, if it tries to use python from the stage directory, which is of the wrong architecture. As a minimum, this should be avoided if cross-build is detected. It is still questionable if this should be the default behaviour rather than in control of the snapcraft.yaml e.g. staging JRE in the snap, vs using JDK from the build environment.